Some new Intel platforms (such as TGL) already have the
fourth fixed counter TOPDOWN.SLOTS, but it has not been
fully enabled on KVM and the host.
Therefore, we limit edx.split.num_counters_fixed to 3,
so that it does not break the kvm-unit-tests PMU test
case and bad-handled userspace.
Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 2 +-
arch/x86/kvm/pmu.h | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8a294f9747aa..0a2c6d2b4650 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -604,7 +604,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
eax.split.bit_width = cap.bit_width_gp;
eax.split.mask_length = cap.events_mask_len;
- edx.split.num_counters_fixed = cap.num_counters_fixed;
+ edx.split.num_counters_fixed = min(cap.num_counters_fixed, MAX_FIXED_COUNTERS);
edx.split.bit_width_fixed = cap.bit_width_fixed;
edx.split.reserved = 0;
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index ab85eed8a6cc..067fef51760c 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -15,6 +15,8 @@
#define VMWARE_BACKDOOR_PMC_REAL_TIME 0x10001
#define VMWARE_BACKDOOR_PMC_APPARENT_TIME 0x10002
+#define MAX_FIXED_COUNTERS 3
+
struct kvm_event_hw_type_mapping {
u8 eventsel;
u8 unit_mask;
--
2.21.3
